A further 50mm to 80mm of rain is expected to fall in the Bay of Plenty today, according to Metservice.
The latest severe weather warning issued by Metservice said heavy rain was expected to continue in the Bay through to early this afternoon.
In the five hours from 9am to 2pm today, a further 50 to 80mm of rain was expected on top of what has already fallen.
Peak intensities of 25mm to 40mm an hour, or possibly more, were expected.
Rainfall of this intensity could cause flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips. Driving conditions would also be hazardous with surface flooding and poor visibility in heavy rain.
There was also a moderate risk of severe thunderstorms in the Western Bay of Plenty this morning.
A severe thunderstorm watch meant conditions were favourable for severe thunderstorms in and close to the watch area. People in these areas should be on the lookout for threatening weather conditions.
For a bit of perspective, Niwa forecaster Chris Brandolino said typical rainfall in Tauranga for the entire month of March was 97mm.
Te Puke usually receives 144mm for all of March and 86mm for Whakatane.
The region is expected to receive a month or more worth of rain in three to five days.
Due to the heavy rain and ongoing bad weather, Waikato Police are urging people to avoid any unnecessary travel around the Coromandel Peninsula today.
Senior Sergeant Dean Anderson from Waikato District Command Centre said several main roads were already water-logged or flooded and the area was effectively cut off.
"More rain is forecast for the rest of the day and high tide is still to come. The situation is just going to get worse.
"Anyone who doesn't need to travel is asked to stay away. We're getting reports of people driving to see the flooding and getting caught out. It's not worth the risk.
"If you do need to travel, please be careful. Check your route before you head out, drive to the conditions and allow extra time for your journeys."